Reinforcing steel

fR

Projected rib factor

fRk

Characteristic projected rib factor

f0.2k

Characteristic 0.2 % proof-stress of reinforcement

ft

Tensile strength of reinforcement

ftk

Characteristic tensile strength of reinforcement

(u

Elongation of reinforcement at maximum load

(uk

Characteristic elongation of reinforcement at maximum load

3.2.1 General

P(1) This section applies to bars, coiled rods and welded fabric, used as reinforcement in concrete structures.

P(2) The requirements apply to the product in the condition in which it is delivered. In the case of coiled rods, the requirements apply to the material after straightening.

(3) The methods of production, the specified characteristics, the methods of testing and the methods of attestation of conformity are as defined in EN 10080 or other relevant documents for reinforcing materials not covered by EN 10080.

P(4) Each product shall be clearly identifiable with respect to the classification system in 3.2.2.

P(5) Tensile strength (ft), yield stress (fy), the ratio of tensile strength to yield stress (ft/fy), the elongation at maximum load (eu), and the projected rib factor (fR) shall all be appropriately specified in relevant Standards and established by standard tests.

(6) For steels complying with this Code, yield stress, tensile strength, the ratio of tensile strength to yield stress, the elongation at maximum load and the projected rib factor should be specified in terms of characteristic values; these values are designated respectively fyk, ftk, (ft/fy)k, £uk, fRk.

3.2.2 Classification and geometry

P(1) The products shall be classified according to:

i) Grade, denoting the value of the specified characteristic yield stress (fyk) in N/mm2.

ii) Class, indicating the ductility characteristics iii) Size iv) Surface characteristics v) Weldability.

P(2) Each consignment shall be accompanied by a certificate containing all the information necessary for its identification with regard to i)-v) in (1) above, and additional information where necessary.

P(3) The actual cross sectional area of the products shall not differ from their nominal cross sectional area by more than the limits specified in relevant Standards.

P(4) In this code, two classes of ductility are defined (see 3.2.4.2):10)

P(5) In this code two shapes of surface characteristics are defined (see 3.2.5.1);

— Ribbed bars, resulting in high bond action (as specified in EN 10080).

— Plain, smooth bars, resulting in low bond action.

10) It is likely that, during the ENV period, a higher ductility steel will be introduced for use in seismic regions (Class S). Until appropriate, design rules are developed for the use of this steel in non-seismic situations (dealing with redistribution, rotation capacity, etc) it will be satisfactory to treat Class S steel as "high ductility".

(6) For other types of bar, with other surface characteristics (ribs or indentations), reference should be made to relevant documents, based on test data.

P(7) Surface characteristics of reinforcing steel with approximately circular cross section shall be indicated by the value of the projected rib factor fR (see 3.2.5.1).

P(8) Welded fabric, used as reinforcing steel, shall comply with the dimensional requirements in relevant Standards.

3.2.3 Physical properties

(1) The following mean values may be assumed:

— coefficient of thermal expansion: 10 x

3.2.4 Mechanical properties

3.2.4.1 Strength

P(1) The yield stress fyk and the tensile strength ftk are defined respectively as the characteristic value of the yield load, and of the characteristic maximum load in direct axial tension, each divided by the nominal cross sectional area.

(2) For products without a pronounced yield stress fyk, the 0,2 % proof stress fo,2k may be substituted. P(3) The ratio of the actual yield stress fy to the specified characteristic yield stress fyk shall not exceed the values specified in relevant Standards.

3.2.4.2 Ductility characteristics

P(1) The products shall have adequate ductility in elongation, as specified in relevant Standards.

(2) Adequate ductility in elongation may be assumed, for design purposes, if the products satisfy the following ductility requirements:

High ductility: euk > |5| %; value of (ft/fy)k > 11081 Normal ductility: euk > |25| %; value of (ft/fy)k > 11051

In which euk denotes the characteristic value of the elongation at maximum load (shown typically in Figure 3.2).

High bond bars with diameters less than 6 mm should not be treated as having high ductility. P(3) The products shall have adequate bendability for the anticipated use.

3.2.4.3 Modulus of elasticity

(1) A mean value of 200 kN/mm2 may be assumed.

3.2.4.4 Fatigue

P(1) Where required, the products shall have adequate fatigue strength.

(2) For fatigue requirements for reinforcing steel, see Part 1E and relevant Standards.

Eurocode Steel Surfaces

3.2.5 Technological properties

3.2.5.1 Bond and anchorage

P(1) The surface characteristics of ribbed bars shall be such that adequate bond is obtained with the concrete, permitting the full force that is assumed in design, to be developed in the reinforcement.

(2) Ribbed bars, having a characteristic projected rib factor (fRk) not less than that in EN 10080 may be assumed to be high bond bars. Bars not satisfying these requirements should be treated as plain bars with respect to bond unless they are defined according to (3) below. (See 5.2.2.2(1) and Table 5.3).

(3) The behaviour in bond of reinforcing steels with other surface shapes should be defined in relevant Standards or technical approval documents.

P(4) The strength of the welded joints along the anchorage length of welded fabric shall be adequate.

(5) The strength of the welded joints of welded fabric may be assumed to be adequate if each welded joint can withstand a shearing force not less than | 30 % | of a force equivalent to the specified characteristic yield stress times the nominal cross sectional area of the anchored wire.

3.2.5.2 Weldability

P(1) The products shall have weldability properties adequate for the anticipated use.

(2) Where required, and where the weldability is unknown, tests should be requested.

(3) Ductility characteristics, as specified in 3.2.4.2, should be maintained, when necessary, at critical sections near to welds.

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Responses

  • imelda
    How to test proof stress in reinforcemant steel?
    8 years ago
  • Keith Endicott
    What fyk for steel means?
    8 months ago
  • felix
    What is b grade rebar Eurocode?
    6 days ago

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